E-mu Systems came to prominence in the early 1980s with its relatively affordable Emulator sampler, and subsequently pioneered sample-based synthesis technology with the Proteus range.
These sounds may then be layered, filtered, modulated by low frequency oscillation and shaped by ADSR envelopes.
The original Proteus series are basic ROMplers which contains 3 base models with 192 patches each, of which 64 are editable by the user.
A cheaper Proteus 1000 model was also introduced with the same soundest and ROM but only 64 voice polyphony and fewer individual sound outputs.
The available ROM chips included the Composer, a work-horse set of sounds useful for popular music production, three orchestral ROMs, the Vintage Keys collection of electric organs, pianos and classic synthesisers, a chip dedicated to the Hammond organ and a drum ROM as well as the Orbit and Mo-Phatt collections, aimed at dance and urban genres and the Xtreme Lead, optimised for monophonic synthesiser soloing.
The E-mu MK-6, XK-6, PK-6 and Ensoniq Halo featured the same 61-key keyboard and controls layout, but slightly different soundset.